This proposal addresses the question of whether events that occur while a person is in a surgical plane of general anesthesia can influence that person's postoperative behavior. Past research relating to this question indicates that, in most cases, surgical patients have no conscious recollection of intraoperative events. However, recent discoveries in the psychology of human memory and its pathology suggest the possibility that while the effects of memory for intraoperative events may not--and probably cannot--be revealed in postoperative tests requiring deliberate, conscious recall or recognition, such effects might become manifest in tests that do not require that patients be aware that they are remembering. To explore this possibilty, five experiments are planned in which surgical patients receiving general anesthesia are presented with auditory information (e.g., common words, simple melodies, or suggestions for relief from postoperative pain), and are later engaged in tests in which retention of this information would be expected to aid performance. In certain tests, patients could attain a passable (above chance) level of performance even if they are not aware that they are remembering the intraoperative information; in other tests, however, passable performance could only be achieved through deliberate, conscious recall or recognition. It is hypothesized that the effects of memory for intraoperative information will be evident in performance of the former type of test, but not in performance of the latter type. The candidate for principal investigator is a cognitive psychologist specializing in the of human memory and amnesia; other professionals involved in the project have expertise in the areas of anesthesiology, psychophysiology, and experimental psychology. The proposed research has important potential implications for psychological theory and surgical practice, particularly with respect to the development of operating room procedures that are beneficial to the mental and physical health of surgical patients.